How To Make A Rotary Switch?

Discussion in 'General Electronics Chat' started by foolios, Aug 29, 2014.

  1. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    I have been looking for a switch and am thinking I don't understand switches.
    I thought for sure I would have found what I was looking for at Radio Shack.
    But I didn't. And now that I am searching online, I am realizing I don't know what I am looking for.
    I want a rotary type switch which will allow me 6 selections for providing power to only one of those 6 positions at a time.
    All I'm finding in my searches appears to be what Radio Shack has.
    Knobs that are just knobs. They don't appear to come as a complete switch but part of the switch. And it appears potentiometers are whats combined in listings.
    Is that what a rotary switch is? A knob added onto a pot?
    If so, I'll run back to RS. And if so, I am prolly gonna have a good laugh with the workers there.
     
  2. ISB123

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  3. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    A rotary switch is NOT a knob added to a pot. It is exactly what you describe, a switch which will allow you to provide power to one of several selections (there are better descriptions, but I wished to use your words). For example, look at this http://www.digikey.com/product-detail/en/56D36-01-1-AJN/GH5603-ND/98652

    The thing is, you may not be able to find exactly 6 positions, but can use a higher number and ignore the positions you don't need.
     
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  4. foolios

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    Feb 4, 2009
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  5. ISB123

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    Yes it will fit.
     
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  6. foolios

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    Feb 4, 2009
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    Thanks! How did you figure it out?
     
  7. ISB123

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    Read the datasheet from rotary switch it says 6.35mm on page 4.
    The flat part is for tightening bolt.
     
    Last edited: Aug 29, 2014
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  8. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    I see it now in the data sheet for the switch. And then in the listing for the knob it also states shaft size of 6.35mm.
    Now I know what to look for.

    Thank you.
     
  9. ISB123

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    Look for D-Shaft Instrument Control Knob if it has a flat side on the shaft.D shaped shaft knobs are less common so look for rotary switch that has star shaped hole.
     
  10. paulktreg

    Distinguished Member

    Jun 2, 2008
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    It's also worth mentioning that you can buy rotary switches with a moveable stop.

    This one at Mouser for example.

    If you read it's a 1 pole 2-12 position. The shaft carries a washer with a protruding metal pin that can be inserted into the switch to restrict the rotary movement at the required number of poles.

    You also need to be aware that some switches make before break or break before make when rotated, something to be aware as either may or may not be something you want in your application.
     
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  11. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    I just read something similar about that difference, but I think in what I read it was called shorted vs non-shorted.
    What does this mean, to make and break?

    By the way, I sent an e-mail to Mouser. $120 to ship two plastic parts less than a 1/4 lb has to be an error. Their shipping is goofed up.
     
  12. ISB123

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    Last edited: Aug 30, 2014
  13. djsfantasi

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    Make before Break means that the next connection is made before the last connection is broken. Also known as a shorting switch. Break before Make means that the last connection is broken before the next connection is made. Also known as a non-shorting switch.
     
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  14. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    O ya, that's a big difference. Thank you for telling me that. That can cause some serious damage, not knowing the difference.
    PHEW!
     
  15. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    If you can get away with it, a slide switch will be cheaper. 300ma sliders are around $2 USD online. Higher current ones are more expensive though.
     
  16. to3metalcan

    Member

    Jul 20, 2014
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  17. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    I just picked one up. Thing is, it doesn't give me it's AC rating. I see it's rated for 30v DC. The one just like it at another site said 30vDC and 120vAC, so I am assuming it's the same.
    Do you know?
     
  18. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    Thanks, I saw it and almost got that one too.
     
  19. ISB123

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    Its rated 30 VAC.The problem is they didn't say if its shorting or not,and since its rated for 30V AC it doesn't mean it can take 30V DC so be careful with voltage you are switching.

     
    Last edited: Aug 30, 2014
  20. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    Yes that's a good point. Many switches have both an AC rating and a DC rating while some do not have both. I would make sure it has the rating i was going to use it with.

    Also while discussing these ratings, let it be noted that some listings of switches show a higher rating than the switch actually has in real life. It can be much different too like 10 times higher. I think it is because they make a typo and type something like "3 amps" instead of "0.3 amps" but this is just ridiculous for some place that sells parts to overlook. This means you must look up and check the data sheet carefully, not rely on the place that is selling the part to post the correct ratings.
     
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